The base price is $4,999 for the basic 8-core,3.2GHz/32GB/1TB/Vega56 iMac Pro configuration.

I am assuming that, for Pro Tools HD Native use only, I do not need the upgraded graphics.

However, upgrading to the next highest level for each of the other three parameters costs $800 apiece. I would love to go from 8-core 3.2 GHz to 10-core 3.0 GHz, 32 GB memory to 64 GB memory, and from 1 TB SSD to 2 TB SSD, but the additional $2,400 would be really stretching my budget.

I do a fair amount of work with sample based-virtual instruments, but not huge orchestral libraries. One instance of Superior Drummer and maybe a dozen synth instances. Output's Exhale and Signal are taxing my current system if I have much else going on. My total sample libraries are under 1 TB. I currently freeze and commit a lot, but I would like to do less of that as I work on arrangements. I work at 24-bit/96 kHz. For the most part, I record only one mono or stereo track at a time.

Probably my biggest wish is to be able to add overdubs late in the process in a mature session with many tracks and maybe some unfrozen VIs, and to be able to track at a low buffer size.

For the workflow I have described, where would you spend on upgrading first? Second? Third?

Been looking myself since my late 2009 is in the shop with a bad video card and hard drive.

At least go for the 10 core. It is the sweet spot since it has the highest burst speed, You will be able to increase ram later albeit from a service center (still will be a lot cheaper), You can do external SSDs later also. not sure it will matter recording through the internal SD (still seems wrong to me) versus usb 3 or TB3.
MHO

Also remember that the system will be half the 1TB. So you can record and mix from the internal. When you are done with the session back it up to an external and clear it from the internal SSD. Thus unless you have a ton of sessions at once you won't necessarily need the 2 TB internal.

I have the RAM upgrade in third place because I currently have 16 GB DDR3 memory and total amount of memory used does not appear to be my bottleneck. Speed, maybe. I am thinking 32 GB should be fine, but I could be mistaken.

In terms keeping the buffer low for late overdubs in large and busy sessions, I feel that more horsepower from the CPU is what I most need. I think I am definitely going 10-core.

The base price is $4,999 for the basic 8-core,3.2GHz/32GB/1TB/Vega56 iMac Pro configuration.

I am assuming that, for Pro Tools HD Native use only, I do not need the upgraded graphics.

However, upgrading to the next highest level for each of the other three parameters costs $800 apiece. I would love to go from 8-core 3.2 GHz to 10-core 3.0 GHz, 32 GB memory to 64 GB memory, and from 1 TB SSD to 2 TB SSD, but the additional $2,400 would be really stretching my budget.

I do a fair amount of work with sample based-virtual instruments, but not huge orchestral libraries. One instance of Superior Drummer and maybe a dozen synth instances. Output's Exhale and Signal are taxing my current system if I have much else going on. My total sample libraries are under 1 TB. I currently freeze and commit a lot, but I would like to do less of that as I work on arrangements. I work at 24-bit/96 kHz. For the most part, I record only one mono or stereo track at a time.

Probably my biggest wish is to be able to add overdubs late in the process in a mature session with many tracks and maybe some unfrozen VIs, and to be able to track at a low buffer size.

For the workflow I have described, where would you spend on upgrading first? Second? Third?

The specs on the processors look like they are down clocked versions of what we have in "PC Land". With that said, most people in Mac land are going to be surprised by how powerful a (almost modern in this case) 8 core processor is. It is going to be more than powerful enough for most people.

Not sure if you don't use external drives or what, but I could not imagine wanting or needing a 2TB OS drive. My OS drive partitions stay at about 150GB and is more than enough. Everything else is on external drives though.

Personally I would wait to see what the new modular Mac Pros look like. But if you need something now...

I just would not pay top dollar for something without expansion/easy upgrade options. Having said that I am running a recent MacBook Pro... as my primary DAW computer...

I would also wait for some teardown reports, and depending on those decide how much to configure in the initial purchase. DRAM is claimed upgradeable but let’s see exactly what is there. CPU will be socketed. etc. So after some while you should have some third party upgrade options.

...and likely down clocked to try to manage thermals, it’s going to get mighty warm inside a high-end iMac Pro...